# What is Supergravity: Definition and 40 Discussions

In theoretical physics, supergravity (supergravity theory; SUGRA for short) is a modern field theory that combines the principles of supersymmetry and general relativity; this is in contrast to non-gravitational supersymmetric theories such as the Minimal Supersymmetric Standard Model. Supergravity is the gauge theory of local supersymmetry. Since the supersymmetry (SUSY) generators form together with the Poincaré algebra a superalgebra, called the super-Poincaré algebra, supersymmetry as a gauge theory makes gravity arise in a natural way.In simple terms, scientists have identified four basic forces behind everything happening around us. They are electromagnetic force (the source of electricity and magnetism), weak force (which relates to radioactivity), strong force (the force that binds up protons and neutrons within the atom) and gravitational force (the reason why apples fall to the ground and the moon revolves around the Earth). Quantum theory can explain the first three types of forces pertinent to the atomic level, however, for big objects, quantum theory is not applicable. Therefore, the gravitational force is only applied in astronomical science and studies.
These two theories simultaneously may explain all, however, scientists were finding a theory that may explain both quantum theory and theory of gravitation together - a theory of everything. The theory of supergravity revolves around this intention, to establish a theory that is applicable everywhere.

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1. ### Suggestions for future reading — Supergravity by Freedman or A First Course in String Theory by Zweibach?

What do you recommend to read first, Supergravity by Freedman or A First Course in String Theory by Zweibach? For future consideration.
2. ### I Rovelli on Quantum Gravity

Rovelli points to three pieces of existing observational evidence that should guide future quantum gravity research. Bottom line: * abandon Lorentz invariance violating quantum gravity theories, * abandon supergravity and string theory, and * stop working on the anti-deSitter/conformal field...
3. ### What are the best textbooks for learning about supergravity?

Hello all! I am trying to find self-consistent introduction to current state of quantum N=8 d=4 supergravity. Other books on supergravity are very welcome as well
4. ### I If 11 dimensional supergravity were nonpertubative quantized

Edward Witten's M-theory conjecture is that there is a theory that has 5 10D superstrings and 11D supergravity as its low energy limit, and is defined nonperturbatively. Now, I know that Urs and Mitchel are not fans of loop quantization program. fine. Urs and Mitchell do not think that a loop...
5. ### Exercise from Supergravity textbook

Homework Statement In Ex. 2.4 from textbook Supergravity by Freedman and Van Proeyen one needs to prove the following identity $$A^\dagger \sigma_\mu A=\sigma_\nu \Lambda^\nu{}_\mu$$ Homework Equations It is easy to prove the other identity in this exercise  A\bar{\sigma}_\mu...
6. ### A Starobinsky Inflation and Supergravity

The available experimental data prefers plateau models of cosmic inflation, and among them Starobinsky inflation (aka R^2 inflation) is preferred, even if maybe not significantly. Since Starobinsky inflation is pure gravity (the inflaton field here is an effective incarnation of a higher...
7. ### Insights General Relativity as a Gauge Theory - Comments

haushofer submitted a new PF Insights post General Relativity as a Gauge Theory Continue reading the Original PF Insights Post.
8. ### Insights 11d Gravity From Just the Torsion Constraint - Comments

Urs Schreiber submitted a new PF Insights post 11d Gravity From Just the Torsion Constraint Continue reading the Original PF Insights Post.
9. ### A Study "De Sitter Supergravity" Effectively

Dear all I just want to ask currently i am studying supergravity. Why it is much important or easier to study the AdS4 supersymmetric de Sitter group and then applying contraction to get superpoincare one than starting directly by gauging superpoincare without any contraction. Thank you
10. ### A Formulating Supergravity Under De Sitter Group: A Comprehensive Reference

Dear all I am studying formulating supergravity under De Sitter group can anyone suggest me a reference Thank you
11. ### A Exploring Torsion in Supergravity: Uncovering the Truth Behind its Nullity

Dear All is the torsion always equal zero in supergravity? Thank you
12. ### How Do Bilinears Connect to Killing Vectors and Differential Forms?

What does it mean that a Killing vector and a total differential of a certain theory are related to bilinears? In other words, why would bilinears (e.g. of the forms ##<\gamma_0\epsilon, \gamma_5\gamma_{\mu}\epsilon>## and ##<\gamma_0\epsilon, \gamma_{\mu}\epsilon>## tell us anything about...
13. ### How to know which gauge transformation we should use?

Spinors in $N=2, D=4$ supergravity can be simplified using gauge transformation and thus canonical spinors can be found. In the case of $N=2, D=4$ supergravity the gauge transformation Spin (3,1) is used. My question is how do we know which transformation can be used in a certain theory in order...
14. ### What does ##\delta F=0## mean?

Links for [1] and [2] are below. Please have a look here section 12.6 [1]. It says here that Given the action of a supergravity theory, it is generally useful to search for solutions of the classical equations of motion. It is most useful to obtain solutions that can be interpreted as...
15. ### Why do those two terms add here?

When I was studying complex manifolds in a Freedman's SUGRA book, I ran across this. In a complex manifold, the metric is...
16. ### Why Complex Scalars in 4D Supersymmetric Theories?

The scalar fields of supersymmetric theories in 4 spacetime dimensions are a set of complex fields (usually denoted by ##z^{\alpha}##). How can this be physically translated? More precisely, we know that in 5D, those scalars are real, so what is that makes them real here but complex there?
17. ### Exploring the Role of Superconformality in Coupling Supergravity to Matter

I have been trying for a while to read a precise definition of a Vector Multiplet (to whom ##N=2## Supergravity theories couple to in ##4D##) but was not lucky in finding a self-contained one. The best I got was that on https://en.wikipedia.org/wiki/Supermultiplet though it was on...
18. ### How do scalars determine the geometry of a manifold?

Crossing over the following paragraph: There are three types of special manifolds which we shall discuss, related to the real scalars of gauge multiplets in D = 5, the complex scalars of D = 4 gauge multiplets and the quaternionic scalars of hypermultiplets. Since there are no scalars in the...
19. ### Why a bosonic background in SUGRA?

In this http://www.ulb.ac.be/sciences/ptm/pmif/Rencontres/specgeom.pdf, for example on p.7 and in many other references, people usually say: we will concentrate on the bosonic part of the Lagrangian in N=1 (sometimes N=2) supergravity. In other incidents, people say, that they are going to...
20. ### D=11 supergravity equations of motion

Quick question, I'm preparing to work on supergravity. For completeness I was deriving the equations of motion for the Bosonic sector of maximal sugra. The Action principle is ##S=\int \star R -\frac{1}{2}\star F_4\wedge F_4 + \frac{1}{6} F_4\wedge F_4\wedge A_3## with ##F_4 = dA_3##. The...
21. ### Insights Homotopy Lie-n Algebras in Supergravity - Comments

Urs Schreiber submitted a new PF Insights post Homotopy Lie-n Algebras in Supergravity Continue reading the Original PF Insights Post.
22. ### Degree of freedom of gravitino

Please tell me how to count the degree of freedom of gravitino on the mass-shell? I read http://arxiv.org/abs/1112.3502, but I can't understand it. How about supervielbein?
23. ### Substitution in the following supersymmetry transformation

I was reading in this book: Supergravity for Daniel Freedman and was checking the part that has to do with Extremal Reissner Nordstrom Black Hole. He was using killing spinors (that I am very new to). I was understanding the theory until he stated with the calculations: He said that the...
24. ### Is M-Theory the only possible UV completion of Supergravity?

Is M-Theory the only possible UV completion of Supergravity?
25. ### Supergravity = local SUSY or gravity mediation?

Hi, in some texts, the term supergravity refers to locallized supersymmetry but most of the times, I have the impression that it refers to gravity mediated supersymmetry breaking (i.e. higher dimensional terms in the kahler- and superpotential that are suppressed by powers of the Planck...
26. ### Vanishing spinor projections in supergravity

Hello all I am working on a model in D=5 N=2 supergravity where the metric background is described by a time-dependent three brane, with one extra spatial dimension (a brane-world with bulk sort of set up). The vanishing of fermionic variations gives me the following weird projections...
27. ### Supergravity, does anyone work on it now?

It is with immense pleasure that I came across this passage in Brief History of Time. I remember reading this sentence when I was 16 but in the last 20 years I had forgotten where I read it. The only thing I could remember was that there were some physics calculations which took 3 years to...
28. ### Exploring the Cosmology of N=8 Supergravity

My ongoing study of https://www.physicsforums.com/showthread.php?t=483871" that this has something to do with the fact that the shear viscosity to entropy ratio of a strongly coupled N=4 super-Yang-Mills plasma is 1/4π. Sheppeard has her own program of deriving field theory from categorical...
29. ### Supergravity paper on LHC-physics by Chris Austin

http://arxiv.org/abs/1103.2732 Abstract "Rough estimates are presented to show that the bump at 1.7 to 1.9 TeV seen in ATLAS-CONF-2010-088 could arise from about 10^{30} approximately degenerate Kaluza-Klein states of the d = 11 supergravity multiplet in the s channel, that could arise from...
30. ### Supergravity as the low energy effective action of Superstring- / M-theory

Hello. I have a question for the specialists on Superstring Theory: I am looking for a reference to original research, where the following is proven / shown / evidence is given / made plausible / etc. - 10D supergravities in their various forms are the low energy limits of superstring...
31. ### Classical gravity, Supergravity and strings

So the following questions were posed in an another thread by Pallen, and I thought i'd give an attempt at answering them, since they tend to show up over and over again. " 1) It is not clear that GR and QFT must be considered in conflict that must be resolved somehow. I've seen a growing...
32. ### Demonstrated convincingly that supergravity gives you GR

Has it ever been demonstrated convincingly that supergravity gives you GR in the continuum limit (as opposed to just some massless spin-2 field)? Where can I find a readable derivation of this fact?
33. ### Where Can I Find Beginner-Friendly Resources on Supergravity?

Can you suggest any lecture notes/review articles/free books available in the internet at introductory level and which uses standard conventions in use at present? Thanks.
34. ### Gauge formulation of gravity and supergravity

Hi, I have a question on the gauge formulation of gravity and supergravity. The question that I have first concerns the gauge formulation of gravity. As I understood from various articles by Sardanashvily (see e.g. D.Ivanenko, G.Sardanashvily, The gauge treatment of gravity, Physics Reports...
35. ### N=8 Supergravity: Maximal Supergravity Explained

Provided that no particles have spins higher than 2, maximal supergravities are defined to be with supergravities with 32 supersymmetries. Why is the N=8 supergravity in four dimensions called 'the maximal supergravity'? I am confused now... Thanks.
36. ### Correct Type IIA supergravity action

Hi, I'm trying to figure out what the correct form is of the Type IIA supergravity action in the String frame. The peculiar thing is that I'm finding different versions in the literature. Let me state two different ones. In Polchinski, the action is given by S = \frac{1}{2\kappa_{10}} \int_X...
37. ### Can E7(7) Symmetry in 60 Dimensions Enhance Understanding of d=11 Supergravity?

http://arxiv.org/abs/0902.1509 E(7(7)) and d=11 supergravity Authors: Christian Hillmann (Submitted on 9 Feb 2009) Abstract: This thesis firstly investigates whether D=11 supergravity can be lifted to a higher dimensional theory without introducing additional bosonic fields by...
38. ### Hyper-complex fields in Supergravity?

Dear colleagues I have recently come across a mathematical reference discussing all possible generalizations of complex numbers. A particularly interesting such generalization is known as split-complex numbers. These are defined: z = x+jy z* = x-jy similarly to ordinary complex numbers...
39. ### Supergravity and local symmetry

In chapter 4 of Bailin & Love, Supersymmetric gauge field theory and string theory, the authors state that supersymmetry is considered a global symmetry, and we can separately consider it to be a local symmetry. Further, since the supersymmetry algebra contains P^\mu, the generator of...
40. ### Teaching myself supersymmetry and supergravity

Hi, I am interested in teaching myself supersymmetry and supergravity. I have a decent qft background. I know of several good online notes,, but what I really need is a source of good problems. Anybody know where I can find such a source? Does the Wess and Bagger book have good problems...